A brute-force attack is attempting to find a secret value by trying all possible values until the correct one is found.
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How much would it cost in U.S. dollars to brute force a 256 bit key in a year?
I am often told that any key can be broken and that it is only a matter of time and resources for any key to be broken. I know that this it technically true. However, I think that there is probably a ...
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2answers
3k views
How long does it take to crack DES and AES?
Suppose that a single evaluation of a block-cipher (DES or AES) takes 10 operations, and the computer can do $10^{15}$ such operations per second.
How long would it take for to recover a DES key, ...
8
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1answer
557 views
Duration for attacking Two-Key Triple-DES Encryption using all RAM ever built?
I am considering attacks on Two-Key Triple-DES Encryption assuming $2^{32}$ known plaintext/ciphertext pairs (that's a mere 32 Giga Bytes of ciphertext) by the method devised by Paul C. van Oorschot ...
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2answers
546 views
Measuring entropy for a ciphertext only attack
When bruteforcing a password (e.g. the common attacks on DES), where you have ciphertext only, you need a way to assess whether a decrypted plaintext is the right one. I believe the EFF DES machine ...
6
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1answer
248 views
How exactly would someone attempt to analyse ciphertext produced by popular encryption products such as Truecrypt/PGP?
I am interested in understanding what the process would be if an attacker wished to attempt to decrypt data secured by common tools such as OpenPGP, Truecrypt or the like. Are there any documented ...
4
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3answers
249 views
Is there some way to generate a non-predictable random number in a decentralised network?
Is there a way to generate a random number with given restrictions:
It will be used in a decentralised network with a big number of peers (no central authority to generate it)
Its generation should ...
4
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4answers
197 views
Could a very long password theoretically eliminate the need for a slow hash?
Before I provide details, I want to clarify that I am not looking to implement this practically, but I'm only asking to get a better understanding.
The way I currently understand it, we use slow ...
4
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4answers
460 views
What is the largest performed/possible bruteforce attack to date?
I've read that cracking 128-bit key is currently out of reach of all humanity. However, I can't seem to find any information on what scope of brute force attacks have been performed or are possible at ...
4
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1answer
136 views
Question about why RSA is hard to attack
I think I understand why RSA is hard to attack but I'd like to get clarification if I actually do.
Assume there are two people, Alice and Bob, who are attempting to communicate privately but that we ...
4
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2answers
213 views
Cost of attacking Mobile OTP with a fake server
You want to obtain a 74-bit secret $K$. There is an oracle that will provide you with the following value for several values of $T$:
...
3
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2answers
515 views
Can a computationally unbounded adversary break any public-key encryption scheme?
Assume there is a public-key encryption scheme $(KeyGen, Enc, Dec)$ with perfect correctness (i.e., for all messages M and valid key-pairs (PK,SK), we have $Dec_{SK}(Enc_{PK}(M))=M$).
Will there ...
3
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2answers
225 views
Is it generally possible to employ brute force methods when the encryption scheme is not known? Why or why not?
Lets say you are presented with an encrypted string of bits or text, and no other information. What would be necessary before you could apply brute force methods to decrypting the string? How would a ...
3
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2answers
244 views
Key space size when either of two public keys are valid for authentication?
If for authentication a user can own either A OR B public key instead of just one specific key is that equivalent to halving the key space. i.e. it it theoretically twice as easy to brute force and ...
3
votes
2answers
843 views
Brute forcing CRC-32
I'm working on a cryptosystem which uses IDEA. The designer made the mistake of including a CRC-32B hash of the password unencrypted in the header, so that the system can quickly reject bad ...
3
votes
2answers
383 views
How to account for moore's law in estimating time-to-crack?
It seems to be common practice (at least in some communities) to tack on the phrase "with current computing power" when estimating the absurdly long time it would take to, for example, brute-force an ...
3
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1answer
171 views
OCB - brute force against unknown IV
I read that brute force attacks against a plaintext encrypted in OCB with unkown key and IV has approximately the same complexity as an attack where only the key is unknown.
Why is that ?
Is there a ...
3
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2answers
121 views
How does using salt reduce rainbow table attack?
I could create a rainbow table for a particular salt value and still create a successful attack similar to one without salt value.
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2answers
703 views
How can I do a brute force (ciphertext only) attack on an CBC-encrypted message?
Given a CBC ciphertext and IV, how can I find the encryption key?
We are limited with an 8 chars key, each char in the range of [a..h], so I can generate every possible key (these are only $8^8 = ...
2
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2answers
952 views
How much computing resource is required to brute-force RSA?
It's been over 30 years since Rivest, Shamir and Adleman first publicly described their algorithm for public-key cryptography; and the intelligence community is thought to have known about it for ...
2
votes
1answer
272 views
Why can't I break ElGamal encryption by brute-forcing the secret exponent?
I am doing a course on cryptography on coursera and one of the topics covered was the ElGamal Encryption system.
I am using the terms as defined in Wikipedia.
Alice publishes $g$ and $g^x$. ...
2
votes
1answer
164 views
SHA256 HMAC brute force with chosen plaintext attacks
This is a follow up to Is It Possible To Reconstruct a Cryptographic Hash's Key
I am using a SHA-256 HMAC function on a single-word input: sha256hmac(privatekey,word) = output. The private key length ...
2
votes
1answer
152 views
estimate of time required to crack sha512crypt password with JtR + OpenCL
OK, I have a shadow file with a password that I know, it is 4 letters followed by two numbers. Using John The Ripper with OpenCL support, on a laptop with AMD Radeon Mobility graphics, how long would ...
2
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1answer
559 views
Cryptanalysis Affine Cipher: Brute-Force Search Vs. Meet-in-the-middle
Affine Cipher:
$Enc(x) = (ax + b) \mod m$
$Dec(x) = a^{-1}(x-b) \mod m$
For a brute-force key search, we need to do $a \cdot b$ encryptions in the worst case.
For a meet-in-the-middle attack, how ...
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3answers
217 views
How to encrypt data and know it will be secure for at least a few decades?
I want to encrypt a small amount (few kilobytes) of data and be fairly confident it will be secure against brute force decryption and advances in cryptanalysis for at least a a few decades (or more). ...
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2answers
71 views
Many consecutive hashes to slow down brute force attack?
I've heard that hash algorithms like bcrypt are more secure because they take longer to complete, and therefore take much longer to prute force, without a noticable ...
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2answers
274 views
Passwords with same SALT. What does this mean?
If the same SALT is used for many passwords on a Linux server, in what way is that a security risk?
Does the mean, that a user (which can change his own password) can calculate other users passwords?
...
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2answers
157 views
Are really, really long passwords any securer than short ones?
Just for fun, I want to encrypt a message that will take about 10 or so years to decrypt. My idea is to encrypt a message with AES-512 with a password one million decimal digits long.
Knowing not ...
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2answers
160 views
Brute force a ciphered message?
I wrote my own cipher to encrypt messages. I would like to test a sample ciphered message to see how strong it is. Are there any tools for such task either in Windows or Linux ?
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2answers
354 views
DES Crack simulation
I wish to simulate an implementation of a DES Cracker using verilog. But every paper I read give only abstract hints but no concrete steps or how really to go about it. How is it usually done? For ...
1
vote
1answer
107 views
Encrypt a single file, chunk-by-chunk, each chunk using different key (AES)
Encrypt a single file, chunk-by-chunk, each chunk using different key.
I am a security newbie (only took 2 security courses before)
But currently I am using this encryption method for my Android ...
1
vote
2answers
181 views
Kryptos : K1. What is the origin of the “palimpsest” keyword?
I'm studying the Kryptos sculpture with its cryptographic puzzles K1 to K4.
I understand that the keyword "palimpsest" was reverse-engineered using the tableau (and brute-force computer processing), ...
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3answers
787 views
Dictionary attack on pass-phrases on common algorithms
I don't yet perfectly understand the difference between brute-force and dictionary attack since this differentiates one attacking the key and another attacking password: apparently attacking passwords ...
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1answer
118 views
Generate an insecure public / private key pair
I am looking for a way to generate an "insecure" public key pair. and by insecure I actually mean a pair that is breakable using brute-force (or other encryption) methods.
As far as I know PGP ...
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2answers
123 views
Kryptos : K2. What is the origin of the “abscissa” keyword?
I'm studying the Kryptos sculpture with its cryptographic puzzles K1 to K4.
Similar to the "palimsest" keyword for K1, the keyword "abscissa" for K2 was determined by brute-force.
To better ...
1
vote
1answer
172 views
Can iterated key expansion in Blowfish slow down bruteforce attacks on small key sizes?
Suppose I have to use 64-bit keys for encryption (e.g. to comply with export restrictions). For this question, assume this key is truly random, and the encryption algorithm is Blowfish.
Blowfish key ...
1
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1answer
348 views
Most effect way to brute force 16 char AES key
I have a file that is encrypted in AES using a 16 char string. The string is (a-zA-Z0-9) and .,?!. It also only contains words from a dictionary (but they can be lower/upper case). What would be the ...
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1answer
171 views
Vulnerabilities of encrypting data with known regularities
I need to encrypt data that has a pre-defined header and footer structure, and furthermore the data follows pre-defined patterns. The header and footer structure follow a defined structure but cannot ...
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0answers
133 views
Academic papers on GPU password cracking? [closed]
Are there any scientific papers or publications on GPU password cracking?
0
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1answer
46 views
chaining rsa with ecies
In an answer to a previous question it was suggested that one way to protect your asymmetrically encrypted AES-256 keys, from say a solution to prime factorization, would be to chain asymmetric ...
0
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2answers
114 views
What is the advantage of an attacker over breaking a 4 digits PIN?
When a hardware system is protected by a 4 digits password, what is the advantage of the attacker into breaking that system?
Isn't it $10*10*10*10=10^{4}$? If $\frac{1}{10^{4}}$ is the cost of such ...
0
votes
1answer
68 views
Is the following key stretching algorithm as memory hard as I think it is?
I'm having some fun designing a key stretching algorithm that can be implemented in pure Python. It's built entirely out of the standard library's hash functions in an attempt to at least wrest some ...
0
votes
1answer
87 views
Obtaining a key that's using ice algorithm
I have a text file that has been processed by the SNOW steganography tool that uses ICE encryption. However, I do not know the key that would enable me to decrypt and retrieve the message hidden.
...
0
votes
1answer
202 views
Brute forcing Cardan grille
Having a "rotating" square Cardan Grill with sides long n cells, how could i determinate the cost of a brute-force attack?
How many configurations should be considered to perform an exhaustive ...
0
votes
0answers
54 views
how many bit flips current computers can carry per second? When brute force is hard?
How many bit flips the fastest current computers can accomplish per time unit? i.e per second. I am trying to find when brute force attacks are considered infeasible. The reason I chose bit flips is ...
0
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0answers
19 views
Kryptos : K3. What is the accepted transposition for a solution?
I'm studying the Kryptos sculpture with its cryptographic puzzles K1 to K4.
It's understood that K3 is solved via transposition, but I have seen several solutions. Which is the best/accepted one?
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1answer
274 views
cracking WINRAR encryption method(AES) using brute force [closed]
if the WINRAR encryption method(AES) is so unbreakable(by brute force), then why doesn't every software use a similiar encryption method?
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1answer
5k views
Uncompress the winRar password protected file without password. (not brute force attacking)
I would like to know how to extract contents of the password protected winrar file without the password. I have downloaded that WinRar file from a file hosting website. I only found out that it was ...
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votes
1answer
145 views
How does one find out ciphers/passwords without knowing what cryptographic algorithms are used?
If one does not reveal what cryptographic algorithms are used, how does a cracker find out a password/cipher that is used to communicate data? I heard that because there are methods to try cracking ...
